With the rapidly expansion of the market for laptop computers, mobile phones, electric vehicles, and the like, a secondary battery having a high energy density is required. Examples of a method for obtaining a secondary battery having a high energy density include a method in which a negative electrode material having a large capacity is used, and a method in which an electrolyte liquid having excellent stability is used.
Patent document 1 discloses using a silicon oxide or a silicate as a negative electrode active substance of a secondary battery. Patent document 2 discloses a negative electrode for a secondary battery which has an active substance layer containing a carbon material particle that can absorb and desorb lithium ion, a metal particle that can be alloyed with lithium, and an oxide particle that can absorb and desorb lithium ion. Patent document 3 discloses a negative electrode material for a secondary battery which is formed by coating the surface of a particle, which has a structure in which a silicon fine crystal is dispersed in a silicon compound, with carbon.
Patent document 4 discloses an electrolyte liquid which contains a cyclic oxocarbon anion having the following structure.
(In the formula, R1 represents one group selected from the group consisting of hydrocarbon groups with a carbon number of 1 to 12, halogen-substituted hydrocarbon groups, alkoxy groups, thioether groups, amino groups, amide groups and acyl group. n is an integer of 1 to 6).
Patent document 5 discloses a secondary battery in which a negative electrode consisting of lithium or a lithium compound is used and in which a halogen atom-substituted cyclic ether with a three-membered or four-membered ring is used as an solvent of an electrolyte liquid.